Should I cut dead leaves off my tomato plant?

QUESTION: Should I cut dead leaves off my tomato plant? I’m not sure if they are hurting the plant or keeping it from making more tomatoes.

When you’re growing tomatoes, you may find yourself wondering whether it’s worth the effort to trim dead or yellowing leaves from your tomato plants. The answer depends largely on the type of tomato plant you are growing: determinate or indeterminate, also known as bush or vine tomatoes. Understanding the differences between these two types will help you determine how much pruning your plants need and why it might benefit their growth.

ANSWER: When it comes to determinate (bush) tomato varieties, pruning dead leaves or yellowing foliage is less about improving fruit production and more about keeping your plants healthy. Determinate plants have a set growth habit, meaning they bloom once, set fruit, and then stop producing after their initial harvest. The total number of tomatoes these plants can produce is largely predetermined by how many flowers they develop, so heavy pruning won’t increase their yield. However, you may still wish to remove dead or yellowing leaves below the first set of flowers. Doing so can improve airflow around the base of the plant, reducing the risk of fungal diseases, and tidy up its appearance. Here’s more on the difference between determinate and indeterminate.

For determinate (or bush) tomato varieties you can also prune the first level of “suckers,” which are the small shoots that grow from the crook where a branch meets the main stem. Removing these low-lying suckers can help redirect the plant’s energy toward developing its fruit while maintaining a manageable size and shape.

You can also remove this first level of “suckers,” which grow from the bend where a branch meets the main stem, as long as they’re below the first flower clusters. It is recommended to prune indeterminate tomato varieties more heavily, however, as these plants can set fruit more than once during the growing season, and pruning dead leaves or unproductive foliage away can help encourage indeterminate plants to focus on the development of fruit instead.

Indeterminate (vine) type of tomato plant varieties, on the other hand, can benefit more significantly from pruning. These plants grow continuously throughout the season and produce fruit multiple times, so careful pruning can encourage them to focus their energy on fruit development rather than maintaining unnecessary foliage. Start pruning your indeterminate tomatoes when the foliage below the first set of flowers begins to turn yellow, which usually happens when the plant reaches about 12 to 18 inches in height. Remove any dead or yellowing leaves and low-lying suckers below the first flower cluster to improve airflow and keep the plant healthy.

As the growing season progresses, you may choose to prune more aggressively. Removing additional suckers higher up the plant can help control its size and prevent overcrowding, but be mindful of the trade-offs. Large or well-established suckers can leave significant wounds when removed, so it’s often best to leave them if they’ve grown too large. Additionally, avoid removing leaves that provide shade to ripening fruits, as too much sun exposure can cause sunscald.

For indeterminate plants, some gardeners recommend limiting the plant to four or five fruit-bearing branches. This practice encourages the plant to focus its resources on producing larger, healthier tomatoes rather than spreading its energy thin across numerous branches and fruits. However, this is a personal choice and may depend on your gardening goals, as well as the specific variety you’re growing.

In summary, whether you’re growing determinate or indeterminate tomatoes, pruning dead leaves and managing foliage can help keep your plants healthy and productive. For determinate varieties, focus on tidying up the lower leaves and suckers, while for indeterminate varieties, more extensive pruning can support fruit production throughout the season. By tailoring your pruning approach to your plant type, you can enjoy healthier plants and a more abundant harvest.